Strange Alternator Problems

[R-U-QUIKR]

I have a brand new alt and battery which worked fine for a few days and then the alt wouldn't make any voltage. Had it bench tested, the alt is fine. So i put it back in and it worked fone for a week but is shitting the bed again. I've cleaned the connections to the battery and tried running a direct power cable from alt to battery with no luck. My last guess is there is something wrong with harness that plugs int the alt so I'm going to cut off the plug and go direct. Does anybody know what each of the 4 wires is for on the harness? Should the alt make power if the harness isn't plug in? Does anybody have any suggestions? I need some help here I'm at my witts end.

 

[bigblock]

This is a long shot, I had the same problem on a 94 spirit, it ended up being the ignition switch

as for the 4 wires most alts. work the same
1) stater wire, 12 volts when ignition switch is on
2)feeds to gauge
3)return from gauge
4)reads draw so the alt. knows how many amps to put out
this is basic wiring please check this info out be for using.
use a volt meter to make sure you have the proper voltage at each wire
use the repair manual that you have it will tell you what each wire is

I don't think you should cut the harness

if the alt. is good than there is a problem getting the signal to tell it to charge
also check the Resistance between neg bat. post and case of the alt. on a 200k scale the resistance should be no more than .04
if the resistance is to high you could be over working the alt. causing it to overheat
I really hope i could help you

 

[turboguy25]

Did you put a volt meter on between the alt +post and battery negative post and read the volts to make sure its putting out volts while its running? If it is then second use the OHM meter to OHm out the wire from the alt to the fuse their should be verry little resitsance their, also check the fuse sometimes it burns and you can't tell unless you pop the clear top off.
And never run a straight wire from alt to batt could cause electrical fire! always use a fuse inline ushally 80 amp

 

[R-U-QUIKR]

Did you put a volt meter on between the alt +post and battery negative post and read the volts to make sure its putting out volts while its running? If it is then second use the OHM meter to OHm out the wire from the alt to the fuse their should be verry little resitsance their, also check the fuse sometimes it burns and you can't tell unless you pop the clear top off.
And never run a straight wire from alt to batt could cause electrical fire! always use a fuse inline ushally 80 amp

The straight wire was fused, the voltmeter read .5volts form the alt post to negative battery when running, hence the problem. Also the main alt fuse is fine, it has been a peridiocal problem.

 

[R-U-QUIKR]

So, I nave been able to get a charge from the alternator by putting a new fitting on the main power cable that attachs to the alternator output but after a hour or so it will no longer make a charge. It actually makes sparks at the alt output if you rev the engine but everythnig is tight. What would cause it to spark?

 

[Bostedquest]

So, I nave been able to get a charge from the alternator by putting a new fitting on the main power cable that attachs to the alternator output but after a hour or so it will no longer make a charge. It actually makes sparks at the alt output if you rev the engine but everythnig is tight. What would cause it to spark?

somewhere it is grounding out/arcing.

 

[R-U-QUIKR]

If it is grounding out shouldn't it be draining the battery if it it is sitting?

 

[R-U-QUIKR]

So the voltage regulator in the new alt was shorting out when it was hot, hence the reason why it didn't show on a bench test. Fixed~!